Is One Twin a "Geminus"?

We all know that the plural of "index" is "indices".  (We all know it, but not all of us says it.)  I walked through a section of my neighborhood this morning, instead of passing by, as usual.  It's a cul-de-sac street made up of double houses.  If the singular is "duplex", should the plural be "duplices"?  If you live in one, are you being duplicitous?

Of course, I am not the first person to play with English-language words.  I must bow my head to Pete Seeger and George Carlin, among others.






It's not all fun and games, though.  I take exception to this sentence from Steeped in Evil by Laura Childs.  "There was, quite literally, a sea of well-dressed women who, by some mysterious circumstance, all seemed to know one another."  Nowadays, if someone says "literally", they're almost certainly using it wrong.  Are the women all wet?  Are they melting?  Are they (literally) "sloshed"?  Both the author and the editor should be slapped for that one.

What exactly would be a "sea" of women:  Charleston harbor during the first part of an all-female triathlon?